Alicia Davis | University of Michigan (original) (raw)

Papers by Alicia Davis

IEEE Transactions on Robotics, Oct 1, 2022

Journal of Neural Engineering, Nov 14, 2022

Objective. Advanced myoelectric hands enable users to select from multiple functional grasps. Cur... more Objective. Advanced myoelectric hands enable users to select from multiple functional grasps. Current methods for controlling these hands are unintuitive and require frequent recalibration. This case study assessed the performance of tasks involving grasp selection, object interaction, and dynamic postural changes using intramuscular electrodes with regenerative peripheral nerve interfaces (RPNIs) and residual muscles. Approach. One female with unilateral transradial amputation participated in a series of experiments to compare the performance of grasp selection controllers with RPNIs and intramuscular control signals with controllers using surface electrodes. These experiments included a virtual grasp-matching task with and without a concurrent cognitive task and physical tasks with a prosthesis including standardized functional assessments and a functional assessment where the individual made a cup of coffee (‘Coffee Task’) that required grasp transitions. Main results. In the virtual environment, the participant was able to select between four functional grasps with higher accuracy using the RPNI controller (92.5%) compared to surface controllers (81.9%). With the concurrent cognitive task, performance of the virtual task was more consistent with RPNI controllers (reduced accuracy by 1.1%) compared to with surface controllers (4.8%). When RPNI signals were excluded from the controller with intramuscular electromyography (i.e. residual muscles only), grasp selection accuracy decreased by up to 24%. The participant completed the Coffee Task with 11.7% longer completion time with the surface controller than with the RPNI controller. She also completed the Coffee Task with 11 fewer transition errors out of a maximum of 25 total errors when using the RPNI controller compared to surface controller. Significance. The use of RPNI signals in concert with residual muscles and intramuscular electrodes can improve grasp selection accuracy in both virtual and physical environments. This approach yielded consistent performance without recalibration needs while reducing cognitive load associated with pattern recognition for myoelectric control (clinical trial registration number NCT03260400).

Plastic and Reconstructive Surgery - Global Open

Extracting motor signals directly from the peripheral nervous system poses challenges in obtainin... more Extracting motor signals directly from the peripheral nervous system poses challenges in obtaining both high amplitude and sustainable signals for upper-limb neuroprosthetic control. To translate peripheral nerve interfaces into the clinical space, these interfaces must provide consistent signals and prosthetic performance. Previously, we have demonstrated that the Regenerative Peripheral Nerve Interface (RPNI) is a biologically stable, bioamplifier of efferent motor action potentials. Here, we assessed the reliability of the RPNI signals in humans for long-term prosthetic control. RPNI signal quality, measured as signal-to-noise ratio, remained greater than 15 for up to 276 and 1054 days in participant 1 (P1), and participant 2 (P2), respectively. Though signal amplitude varied between sessions, P2 maintained prosthetic performance above 94% accuracy for 604 days without recalibration. Additionally, P2 completed a real-world multi-sequence coffee task with 99% accuracy 611 days wit...

Journal of Neural Engineering

Objective. Extracting signals directly from the motor system poses challenges in obtaining both h... more Objective. Extracting signals directly from the motor system poses challenges in obtaining both high amplitude and sustainable signals for upper-limb neuroprosthetic control. To translate neural interfaces into the clinical space, these interfaces must provide consistent signals and prosthetic performance. Approach. Previously, we have demonstrated that the Regenerative Peripheral Nerve Interface (RPNI) is a biologically stable, bioamplifier of efferent motor action potentials. Here, we assessed the signal reliability from electrodes surgically implanted in RPNIs and residual innervated muscles in humans for long-term prosthetic control. Main results. RPNI signal quality, measured as signal-to-noise ratio, remained greater than 15 for up to 276 and 1054 d in participant 1 (P1), and participant 2 (P2), respectively. Electromyography from both RPNIs and residual muscles was used to decode finger and grasp movements. Though signal amplitude varied between sessions, P2 maintained real-t...

Despite the numerous prosthetic hand designs that are commercially available, people with upper l... more Despite the numerous prosthetic hand designs that are commercially available, people with upper limb loss still frequently report dissatisfaction and abandonment. Over the past decade there have been numerous advances in prosthetic design, control, sensation, and device attachment. Each offers the potential to enhance function and satisfaction, but most come at high costs and involve surgical risks. Here, we discuss potential barriers and solutions to promote the widespread use of novel prosthetic technology. With appropriate reimbursement, multidisciplinary care teams, device-specific rehabilitation, and patient and clinician education, such technology has the potential to revolutionize the field and improve patient outcomes.

Journal of NeuroEngineering and Rehabilitation, 2015

medRxiv : the preprint server for health sciences, 2020

Currently available prosthetic hands are capable of actuating anywhere from five to 30 degrees of... more Currently available prosthetic hands are capable of actuating anywhere from five to 30 degrees of freedom (DOF). However, grasp control of these devices remains unintuitive and cumbersome. To address this issue, we propose directly extracting finger commands from the neuromuscular system via electrodes implanted in residual innervated muscles and regenerative peripheral nerve interfaces (RPNIs). Two persons with transradial amputations had RPNIs created by suturing autologous free muscle grafts to their transected median, ulnar, and dorsal radial sensory nerves. Bipolar electrodes were surgically implanted into their ulnar and median RPNIs and into their residual innervated muscles. The implanted electrodes recorded local electromyography (EMG) with Signal-to-Noise Ratios ranging from 23 to 350 measured across various movements. In a series of single-day experiments, participants used a high speed pattern recognition system to control a virtual prosthetic hand in real-time. Both par...

An exploration of grip force regulation with a low-impedance myoelectric prosthesis featuring ref... more An exploration of grip force regulation with a low-impedance myoelectric prosthesis featuring referred haptic feedback

Achieving dexterous volitional control of an upper-limb prosthetic device will require multimodal... more Achieving dexterous volitional control of an upper-limb prosthetic device will require multimodal sensory feedback that goes beyond vision. Haptic display is well-positioned to provide this additional sensory information. Haptic display, however, includes a diverse set of modalities that encode information differently. We have be-gun to make a comparison between two of these modalities, force feedback spanning the elbow, and amplitude-modulated vibrotac-tile feedback, based on performance in a functional grasp and lift task. In randomly ordered trials, we assessed the performance of N=11 participants (8 able-bodied, 3 amputee) attempting to grasp and lift an object using an EMG controlled gripper under three feed-back conditions (no feedback, vibrotactile feedback, and force feed-back), and two object weights that were undetectable by vision. Preliminary results indicate differences between able-bodied and amputee participants in coordination of grasp and lift forces. In ad-dition, ...